Solution:
The Lattice MachXO2 devices can be updated in the field by utilizing Lattice's background programming mode and TransFR Technology
Background programming:
The on-chip flash can be programmed in background mode, while the device and IOs continue to function as per the user logic loaded into the SRAM memory. JTAG, I2C, SSPI & Wishbone modes can be used to program the on-chip flash in background mode. For more details , read MachXO2 Programming and Configuration Usage Guide :
TN1204 . To program the device in background mode using Diamond Programmer, select "Flash Background Mode" as the Access Mode in the Device Properties Dialogue Box.
TransFR Technology :
After the Flash has been programmed, the contents should be transferred to the SRAM memory, which contains the active configuration, essentially the "fuses" that define the circuit connections. Generally, the IOs are Tri-stated during this transfer, but with Lattice's TransFR Technology, the IO state can be customized i.e. captured to the last state or driven to a user-defined level.
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here to know more about Lattice TransFR Technology :
The Lattice TransFR Technology can only be utilized in JTAG mode, because during transfer, IOs are controlled by the boundary scan cells, accessible only through JTAG port .